Killing fish to save frogs

Shortly after World War II, California fish managers had a brainstorm: They loaded juvenile trout into airplanes and saturation-bombed naturally fishless lakes in the High Sierra Mountains of California. Some of the fish hit rocks and ice, but most hit water.

Gorging on zooplankton, insects and two kinds of mountain yellow-legged frogs, the alien invaders unraveled aquatic and terrestrial ecosystems, often in designated wilderness.

In 2014, the U.S. Fish and Wildlife Service listed both groups of frogs as endangered, prompting aggressive action by Sequoia and Kings Canyon National Parks. The agency plan called for eradicating trout in 110 lakes, though trout would remain in 465 park lakes and hundreds of stream miles, leaving plenty of fishing opportunities.

Gillnets would be used where possible. But in 33 lakes, the only option was rotenone, a short-lived, organic fish poison derived from plant roots and applied at 100 parts per billion. In modern fisheries management, rotenone has never been seen to permanently affect a native ecosystem except to restore it. For centuries, Indigenous peoples have used high concentrations to kill fish for consumption. Rotenone only affects gill tissue.

But as early as 2008, numerous anglers, media and local politicians were throwing hissy fits about an effort to protect mountain yellow-legged frogs merely by suspending trout stocking in 175 waters within national forests.

“If the yellow-legged frog disappears, would anyone notice? Seriously. Does anyone really care?” editorialized Feather Publishing in its six newspapers. And Terry Swofford, chair of the Plumas County Board of Supervisors, declared: “To me, this is just another way of destroying our economy.”

When the environmental review process for frog recovery in Sequoia and Kings Canyon National Parks was completed in 2016, it generated plenty of support from environmental and angling communities. But there was still opposition.

Leading the charge against frog recovery via rotenone, and even gillnets, was the environmental group Wilderness Watch. “Poison has no place in wilderness,” it proclaims, wherever rotenone treatments are planned in the wilderness.

But the Wilderness Act explicitly provides for the use of poisons to eradicate alien species. Federal permits are routinely issued.

Still, many opponents echoed Wilderness Watch’s false assertion that rotenone is “linked” to Parkinson’s disease. The myth derives from an Emory University study designed to create Parkinson’s-like symptoms, not the disease itself. Concentrated rotenone was pumped into rats’ veins for five weeks. No rat developed the disease, just Parkinson’s-like tremors.